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Half-Quantum Vortices

Observation of Half-Quantum Vortices in an Exciton-Polariton Condensate

K. G. Lagoudakis, T. Ostatnicky, A. V. Kavokin, Y. G. Rubo, R. André and B. Deveaud-Plédran

Singly quantized vortices have already been observed in many systems, including the superfluid helium, Bose-Einstein condensates of dilute atomic gases, and condensates of exciton-polaritons in the solid state. Two-dimensional superfluids carrying spin are expected to demonstrate a different type of elementary excitations referred to as half-quantum vortices, characterized by a {pi} rotation of the phase and a {pi} rotation of the polarization vector when circumventing the vortex core. We detect half-quantum vortices in an exciton-polariton condensate by means of polarization-resolved interferometry, real-space spectroscopy, and phase imaging. Half-quantum vortices coexist with single-quantum vortices in our sample.

Read paper on sciencemag.org

Posted by Roland Cerna at 14:52
Time Resolved Cathodoluminescence
We have correlated time resolved CL and AFM images on InGaN quantum wells. This has allowed us to provide a possible explanation for the very high luminescence efficiency of such quantum wells, despite the presence of a large density of dislocations.

High spatial resolution picosecond cathodoluminescence of InGaN quantum wells

S. Sonderegger, E. Feltin, M. Merano, A. Crottini, J.F. Carlin, R. Sachot, B. Deveaud, N. Grandjean, and J.D. Ganière

Appl. Phys. Lett., 89, 232109 (2006)

Posted by Ounsi El Daïf at 11:46